Webvan Group Inc. said its net loss widened to $148 million in the third quarter because of mounting expenses and charges related to its recently completed acquisition of HomeGrocer.com Inc. (www.homegrocer.com )

The Foster City, Calif., online grocery service said that on a per-share basis it posted a net loss of 40 cents share. These figures include one-time charges of $54.8 million for restructuring and amortization and reflect...